U.S. patent number 9,538,990 [Application Number 13/946,205] was granted by the patent office on 2017-01-10 for ultrasonic diagnostic apparatus and ultrasonic diagnostic apparatus control method.
This patent grant is currently assigned to Toshiba Medical Systems Corporation. The grantee listed for this patent is TOSHIBA MEDICAL SYSTEMS CORPORATION. Invention is credited to Tatsuro Baba, Go Tanaka, Isao Uchiumi, Cong Yao.
United States Patent |
9,538,990 |
Baba , et al. |
January 10, 2017 |
Ultrasonic diagnostic apparatus and ultrasonic diagnostic apparatus
control method
Abstract
According to one embodiment, an ultrasonic diagnostic apparatus
is configured to execute an imaging mode of alternately executing a
continuous wave Doppler mode of acquiring time-series Doppler data
by performing continuous wave transmission/reception with respect
to an object and a B mode of acquiring tomogram data represented by
luminance by transmitting and receiving a pulse wave to and from
the object, the apparatus includes a data acquisition unit
configured to acquire continuous wave Doppler data and the tomogram
data by alternately executing the continuous wave Doppler mode and
the B mode while switching the modes, and a display unit configured
to simultaneously display Doppler spectrum information generated
based on the continuous wave Doppler data and a tomogram generated
based on the tomogram data.
Inventors: |
Baba; Tatsuro (Otawara,
JP), Yao; Cong (Otawara, JP), Tanaka;
Go (Otawara, JP), Uchiumi; Isao (Nasushiobara,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
TOSHIBA MEDICAL SYSTEMS CORPORATION |
Otawara-shi, Tochigi-ken |
N/A |
JP |
|
|
Assignee: |
Toshiba Medical Systems
Corporation (Otawara-shi, JP)
|
Family
ID: |
44483772 |
Appl.
No.: |
13/946,205 |
Filed: |
July 19, 2013 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20130303908 A1 |
Nov 14, 2013 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
13108314 |
May 16, 2011 |
|
|
|
|
Foreign Application Priority Data
|
|
|
|
|
May 19, 2010 [JP] |
|
|
2010-115547 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01S
7/52074 (20130101); G01S 15/8979 (20130101); A61B
8/463 (20130101); A61B 8/5246 (20130101); A61B
8/13 (20130101); A61B 8/06 (20130101); G01S
7/52034 (20130101); G01S 7/52066 (20130101) |
Current International
Class: |
A61B
8/13 (20060101); G01S 15/89 (20060101); G01S
7/52 (20060101); A61B 8/00 (20060101); A61B
8/06 (20060101); A61B 8/08 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
101336830 |
|
Jan 2009 |
|
CN |
|
101449984 |
|
Jun 2009 |
|
CN |
|
0 222 913 |
|
May 1987 |
|
EP |
|
0 475 100 |
|
Mar 1992 |
|
EP |
|
2615519 |
|
Jan 1993 |
|
JP |
|
3642834 |
|
Feb 1997 |
|
JP |
|
2001-149370 |
|
Jun 2001 |
|
JP |
|
Other References
EP Extended Search Report for corresponding EP Application No.
11250533.4 mailed on Sep. 9, 2011. cited by applicant .
CN Office Action with English translation for CN Application No.
201110169347.5 mailed on Dec. 20, 2012. cited by applicant.
|
Primary Examiner: Remaly; Mark
Attorney, Agent or Firm: Yoshida; Kenichiro
Claims
What is claimed is:
1. An ultrasonic diagnostic apparatus which is configured to
execute an imaging mode of alternately executing a continuous wave
Doppler mode of acquiring time-series continuous wave Doppler data
by transmitting and receiving a continuous wave to and from an
object and a B mode of acquiring tomogram data that represents
luminance by transmitting and receiving a pulse wave to and from
the object, the apparatus comprising: a Doppler processing
circuitry configured to to calculate a transient response component
generated due to switching between the continuous wave Doppler mode
and the B mode; to subtract the calculated transient response
component from the continuous wave Doppler data to generate a
remainder of the continuous wave Doppler data; to generate Doppler
spectrum information by using the remainder of the continuous wave
Doppler data; and a display configured to display the Doppler
spectrum information in a predetermined format.
2. The apparatus according to claim 1, wherein the Doppler
processing circuitry identifies information for a system by a
parametric model using a biological signal of the object as an
external input, and estimates lost Doppler data due to switching
between the continuous wave Doppler mode and the B mode according
to the information for the system, and interpolates the continuous
wave Doppler data by using the lost Doppler data.
3. The apparatus according to claim 2, wherein the Doppler
processing circuitry estimates the lost Doppler data by multiplying
a first spectrum component corresponding to temporal past of the
lost Doppler data and a second spectrum component corresponding to
temporal future of the lost Doppler data to generate products by a
temporally changing weighting function and adding the products.
4. The apparatus according to claim 3, wherein the temporally
changing weighting function is a cosine function.
5. The apparatus according to claim 1, wherein the Doppler
processing circuitry calculates a transient response component
originating from a preceding stage portion of a wall filter of the
Doppler processing circuitry.
6. The apparatus according to claim 1, wherein the Doppler
processing circuitry calculates a transient response component
generated in a wall filter and frequency analysis circuitry of the
Doppler processing circuitry.
7. The apparatus according to claim 1, wherein the Doppler
processing circuitry calculates the transient response component
from a spectrum having a power dimension by executing
positive-negative symmetric post filter processing, and the Doppler
processing circuitry subtracts the transmission component after the
post filter processing from the continuous wave Doppler data having
a power dimension.
8. The apparatus according to claim 1, wherein the Doppler
processing circuitry calculates the transient response component as
a time axis waveform by changing a magnitude of the transient
response component according to a preset step response waveform
table, and the Doppler processing circuitry subtracts the transient
response component as the time axis waveform from the continuous
wave Doppler data of the time axis waveform.
9. The apparatus according to claim 1, wherein the Doppler
processing circuitry calculates the transient response component by
using an output from an A/D converter of the Doppler processing
circuitry.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority
from Japanese Patent Application No. 2010-115547, filed May 19,
2010; the entire contents of which are incorporated herein by
reference.
FIELD
Embodiments described herein relate generally to an ultrasonic
diagnostic apparatus and an ultrasonic diagnostic apparatus control
method.
BACKGROUND
The present application relates to an ultrasonic diagnostic
apparatus which can execute a continuous wave Doppler (CWD)/B
simultaneous mode of simultaneously displaying a Doppler spectrum
image captured by CWD and a tomogram captured by the B mode in
cardiac diagnosis.
Ultrasonic diagnosis allows to display in real time how the heart
beats or the fetus moves, by simply bringing an ultrasonic probe
into contact with the body surface. This technique is highly safe,
and hence allows repetitive examination. Furthermore, this system
is smaller in size than other diagnostic apparatuses such as X-ray,
CT, and MRI apparatuses and can be moved to the bedside to be
easily and conveniently used for examination. In addition,
ultrasonic diagnosis is free from the influences of exposure using
X-rays and the like, and hence can be used in obstetric treatment,
treatment at home, and the like.
Recently, in cardiac diagnosis, image diagnosis called PWD (Pulse
Wave Doppler)/B simultaneous mode has been executed by using such
an ultrasonic diagnostic apparatus. The PWD/B simultaneous mode is
a mode of executing Doppler spectrum imaging by continuous wave
Doppler and B-mode tomography at a predetermined timing and
displaying the captured images in real time. The PWD/B simultaneous
mode includes an imaging method called interleaved scan and an
imaging method called segment scan. Interleaved scan is a technique
of repeatedly executing, for example, one B-mode scan per four
times of execution of Doppler scan. Segment scan is a technique of
alternately repeating a period (Doppler segment period) of
repeating transmission/reception in the Doppler mode by a
predetermined number of times and a period (non-Doppler segment
period) of repeating transmission/reception in the B mode by a
predetermined number of times.
The CWD/B simultaneous mode, however, requires switching of
continuous waves unlike a case in which PWD is used. For this
reason, a B-mode image is displayed in the freeze mode during a
period in which real-time display is performed in the Doppler mode.
This makes it difficult to simultaneously implement real-time
display of both a Doppler spectrum and a B-mode image in the CWD/B
simultaneous mode, although the implementation of such technique is
clinically demanded.
In order to improve the real-time performance of the CWD/B
simultaneous mode, it is necessary to solve, for example, the
following two problems. One is the problem of losses in
intermittent execution of continuous STFT (Short Time Fourier
Transform) analysis. For example, a large loss of about 50 ms
occurs per frame in B-mode images. Even if interpolation of a loss
of a maximum of about 16 ms is performed for this loss, the problem
of image quality deterioration occurs. The other is the problem of
strong transient responses (30 ms to 100 ms) due to the necessity
to instantly switch B-mode scan and Doppler-mode scan. This
transient response causes noise such as spike noise in a Doppler
spectrum, resulting in degrade of image quality.
It is possible to handle the problem of losses in intermittent
execution of continuous STFT analysis by using the spectrum loss
interpolation technique disclosed in, for example, Jpn. Pat. Appln.
KOKAI Publication No. 2001-149370, which uses an ARX model using an
ECG waveform as a deterministic external input. However, there is
no corresponding unit for the other problem of transient
responses.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing the arrangement of an ultrasonic
diagnostic apparatus 10 according to an embodiment;
FIG. 2 is a block diagram showing an example of an arrangement
provided for a Doppler processing unit 24 to implement a loss
interpolation function and a transient response reduction
function;
FIG. 3 is a view for explaining the operation of the Doppler
processing unit 24 in transient response reduction processing;
FIG. 4 is a view for explaining the execution timing of transient
response reduction processing;
FIG. 5 is a view for explaining filter processing equivalent to
transient response reduction processing;
FIG. 6 is a graph for explaining a transient response;
FIG. 7 is a graph showing an example of a transient response
spectrum at the time when a wall filter acts;
FIG. 8 is a graph showing an example of a transient response
spectrum at the time when the wall filter does not act;
FIG. 9 is a view for explaining the concept of loss interpolation
processing executed by an interpolation processing unit 24m;
and
FIGS. 10A, 10B, and 10C are views for explaining the effect of loss
interpolation processing.
DETAILED DESCRIPTION
In general, according to one embodiment, an ultrasonic diagnostic
apparatus is configured to execute an imaging mode of alternately
executing a continuous wave Doppler mode of acquiring time-series
Doppler data by performing continuous wave transmission/reception
with respect to an object and a B mode of acquiring tomogram data
represented by luminance by transmitting and receiving a pulse wave
to and from the object, the apparatus comprising: a data
acquisition unit configured to acquire continuous wave Doppler data
and the tomogram data by alternately executing the continuous wave
Doppler mode and the B mode while switching the modes; and a
display unit configured to simultaneously display Doppler spectrum
information generated based on the continuous wave Doppler data and
a tomogram generated based on the tomogram data.
The embodiments will be described below with reference to the views
of the accompanying drawing. Note that the same reference numerals
in the following description denote constituent elements having
almost the same functions and arrangements, and a repetitive
description will be made only when required.
First Embodiment
FIG. 1 is a block diagram showing the arrangement of an ultrasonic
diagnostic apparatus 10 according to this embodiment. As shown in
FIG. 1, the ultrasonic diagnostic apparatus 10 includes an
ultrasonic probe 12, an input device 13, a monitor 14, an
ultrasonic transmission unit 21, an ultrasonic reception unit 22, a
B-mode processing unit 23, a Doppler processing unit 24, an image
generation unit 25, an image memory 26, an image combining unit 27,
a control processor (CPU) 28, a storage unit 29, an interface unit
30, and a software storage unit 31. The ultrasonic transmission
unit 21, ultrasonic reception unit 22, and the like incorporated in
an apparatus body 11 are sometimes implemented by hardware such as
integrated circuits and other times by software programs in the
form of software modules. The function of each constituent element
will be described below.
The ultrasonic probe 12 includes a plurality of piezoelectric
transducers which generate ultrasonic waves based on driving
signals from the ultrasonic transmission unit 21 and convert
reflected waves from an object into electrical signals, a matching
layer provided for the piezoelectric transducers, and a backing
member which prevents ultrasonic waves from propagating backward
from the piezoelectric transducers. When ultrasonic waves are
transmitted from the ultrasonic probe 12 to an object P, the
transmitted ultrasonic waves are sequentially reflected by the
discontinuity surface of acoustic impedance of an internal body
tissue, and are received as echo signals by the ultrasonic probe
12. The amplitude of such an echo signal depends on an acoustic
impedance difference on the discontinuity surface by which the echo
signal is reflected. The echo produced when a transmitted
ultrasonic pulse is reflected by the surface of a moving blood
flow, cardiac wall, or the like is subjected to a frequency shift
depending on the velocity component of the moving body in the
ultrasonic transmission direction due to the Doppler effect.
The input device 13 is connected to the apparatus main body 11 and
includes a trackball, various types of switches, buttons, a mouse,
and a keyboard which are used to input, to the apparatus main body
11, various types of instructions and conditions, an instruction to
set a region of interest (ROI), various types of image quality
condition setting instructions, and the like from an operator.
The monitor 14 displays morphological information and blood flow
information in the living body based on video signals from the
image combining unit 27.
The ultrasonic transmission unit 21 includes a trigger generation
circuit, delay circuit, and pulser circuit (none of which are
shown). The pulser circuit repetitively generates rate pulses for
the formation of transmission ultrasonic waves at a predetermined
rate frequency fr Hz (period: 1/fr sec). The delay unit gives each
rate pulse a delay time necessary to focus an ultrasonic wave into
a beam and determine transmission directivity for each channel.
Changing this delay information can arbitrarily adjust the
transmission direction from the probe transducer surface. The
trigger generation circuit applies a driving pulse to the
ultrasonic probe 12 at the timing based on this rate pulse.
The ultrasonic reception unit 22 includes an amplification circuit,
A/D converter, and an adder. The amplification circuit amplifies an
echo signal captured via the probe 12 for each channel. The A/D
converter gives the amplified echo signals delay times necessary to
determine reception directivities. The adder then performs addition
processing for the signals. With this addition, the reflection
component of the echo signal from the direction corresponding to
the reception directivity is enhanced, and a composite beam for
ultrasonic transmission/reception is formed in accordance with the
reception directivity and transmission directivity.
The B-mode processing unit 23 receives an echo signal from the
ultrasonic reception unit 22, and performs logarithmic
amplification, envelope detection processing, and the like for the
signal to generate data whose signal intensity is expressed by a
luminance level. In this case, changing the detection frequency can
change the frequency band for visualization. This arrangement also
allows to concurrently perform detection processing with two
detection frequencies for one reception data. Using this technique
can generate a bubble image and a tissue image from one reception
signal. The data processed by the B-mode processing unit 23 is
output to the image generation unit 25, and is reconstructed as a
B-mode image whose reflected wave intensity is expressed by a
luminance.
The Doppler processing unit 24 frequency-analyzes velocity
information from the echo signal received from the reception unit
22 to extract a blood flow, tissue, and contrast medium echo
component by the Doppler effect, and obtains blood flow information
such as an average velocity, variance, and power at multiple
points. The obtained blood flow information is sent to the image
generation circuit 25, and is displayed in color as an average
velocity image, a variance image, a power image, and a combined
image of them on the monitor 14.
In addition, in order to implement a loss interpolation function
and transient response reduction function (to be described later),
the Doppler processing unit 24 includes a wall filter 24b, a window
function processing unit 24c, a Fourier transform unit 24d, a
bandpass filter 24f, a power estimation unit 24g, a bias pattern
calculation unit 24h, a dynamic post filter 2D table 24i, a time
readout unit 24j, an integrator 24k, a difference processing unit
24l, an interpolation processing unit 24m, and a logarithmic
compression unit 24n, as shown in FIG. 2. The details of processing
executed by each constituent element will be described later.
The image generation unit 25 generates an ultrasonic diagnostic
image as a display image by converting the scanning line signal
string for ultrasonic scanning into a scanning line signal string
in a general video format typified by a TV format. The image
generation unit 25 is equipped with a storage memory which stores
image data. For example, this unit allows the operator to call up
an image recorded during examination after diagnosis. The image
generation unit 25 also has a function as an image processing
apparatus. When constructing, for example, volume data, the image
generation unit 25 constructs volume data by spatially arranging
scanning line signal strings obtained by ultrasonically scanning a
three-dimensional region or continuous two-dimensional regions and
executing coordinate transformation, interpolation processing, and
the like, as needed. The image generation unit 25 generates a
predetermined three-dimensional image by executing volume rendering
using the obtained volume data, MPR processing by extracting an
arbitrary tomogram in the volume data, and the like. Note that each
type of image processing method or the like in the image generation
unit 25 may be implemented by either a software method or a
hardware method.
The image memory 26 temporarily stores ultrasonic data
corresponding to a plurality of frames or a plurality of
volumes.
The image combining unit 27 combines the image received from the
image generation unit 25 with character information of various
types of parameters, scale marks, and the like, and outputs the
resultant signal as a video signal to the monitor 14.
The control processor (CPU) 28 has the function of an information
processing apparatus (computer) and controls the operation of the
main body of this ultrasonic diagnostic apparatus. The control
processor 28 reads out, from the storage unit 29, a program for
implementing various types of image processing methods and programs
for implementing the transient response reduction function and loss
interpolation function (to be described later), expands the
programs in a memory (not shown), and executes computation,
control, and the like associated with each type of processing.
The storage unit 29 stores programs for executing various kinds of
scan sequences, dedicated programs for implementing the transient
response reduction function and loss interpolation function (to be
described later), control programs for executing image generation
and display processing, diagnosis information (patient ID, findings
by doctors, and the like), a diagnostic protocol,
transmission/reception conditions, a body mark generation program,
and other data. The storage unit 29 is also used to store images in
the image memory 26, as needed. It is possible to transfer data in
the storage unit 29 to an external peripheral device via the
interface unit 30.
The interface unit 30 is an interface associated with the input
device 13, a network, and a new external storage device (not
shown). The interface unit 30 can transfer, via a network, data
such as ultrasonic images, analysis results, and the like obtained
by this apparatus to another apparatus.
(Transient Response Reduction Function and Loss Interpolation
Function)
The transient response reduction function and loss interpolation
function of the ultrasonic diagnostic apparatus 10, which are used
for imaging based on the CWD/B simultaneous mode, will be described
next. The transient response reduction function reduces noise due
to a transient response by estimating/calculating a response
spectrum (two dimensions including a time domain and a frequency
domain) of a transient response excited and generated by noise
(e.g., direct component (DC) variations or the like caused by an
analog switch) mixed due to intermittent transmission/reception
upon switching between the Doppler mode and the B mode in imaging
based on the CWD/B simultaneous mode, and subtracting the spectrum
from the frequency analysis result. The loss interpolation function
is a function of identifying a system by a parametric model using a
biological signal typified by an ECG (electrocardiogram) waveform
as a deterministic external input, and predicting and interpolating
a loss spectrum when continuous STFT analysis is intermittently
performed by using the identified system, in imaging based on the
CWD/B simultaneous mode.
Obviously, it is preferable to implement both the loss
interpolation function and the transient response reduction
function described above in the ultrasonic diagnostic apparatus
which performs the CWD/B simultaneous mode. Obviously, however, it
is possible to selectively implement or operate the loss
interpolation function or the transient response reduction
function, as needed. In addition, the CWD/B simultaneous mode to
which the loss interpolation function and the transient response
reduction function are applied may be interleaved scan or segment
scan.
(Transient Response Reduction Processing)
FIG. 3 is a view for explaining the operation of the Doppler
processing unit 24 in processing (transient response reduction
processing) based on the transient response reduction processing.
As shown in FIGS. 2 and 3, upon receiving I and Q signals from the
processing unit at the end of the preceding stage, the bandpass
filter 24f executes filter processing to pass only a predetermined
band of each signal. The power estimation unit 24g estimates the
power of a Doppler signal based on the I and Q signals after the
filter processing. The bias pattern calculation unit 24h calculates
a bias pattern (an STFT response generated by a transient response)
at the time of switching between a B segment and a Doppler segment.
Note that the calculation technique to be used is not specifically
limited.
In addition, the dynamic post filter 2D table 24i dynamically
selects a positive-negative symmetric simplified filter having a
power dimension in response to a B mode/CWD mode switching timing
signal from the control processor 28. The time readout unit 24j
gives a selected simplified filter a predetermined time
corresponding to a B mode/CWD mode switching timing.
The integrator 24k estimates a response spectrum component of a
transient response by integrating the bias pattern calculated by
the bias pattern calculation unit 24h with the post filter output
from the time readout unit 24j. The difference processing unit 24l
reduces a noise component (offset value) due to a transient
response by subtracting the estimated response spectrum of the
transient response from the spectrum component output from the
Fourier transform unit 24d.
The above transient response reduction processing is executed in
CWD/B simultaneous mode imaging in accordance with an inherent
transient response component generated for each switching operation
from a B segment to a Doppler segment, as shown in FIG. 4.
Therefore, the subtraction processing of subtracting the estimated
response spectrum component of the transient response from the
(bare) spectrum component detected by the CWD mode in the filter
processing unit 24l is equivalent in effect to adaptive filter
processing, as shown in FIG. 5.
The above transient response reduction processing makes it possible
to reduce the influence of a transient response caused by switching
from the B mode to the CWD mode even if a transient response like
that shown in FIG. 6 occurs due to variations in the direct current
component of a received Doppler signal. The graph shown in FIG. 7,
which shows temporal changes in spectrum in a superimposed state,
represents a response after wall filter processing. In contrast,
the graph shown in FIG. 8, which shows temporal changes in spectrum
in a superimposed state, represents a response without wall filter
processing. As shown in FIG. 7, the difference processing unit at
the subsequent stage can implement correction by estimating the
influence of the wall filter from a transient response.
(Loss Interpolation Processing)
FIG. 9 is a view for explaining the concept of processing (loss
interpolation processing) based on the loss interpolation function
executed in the interpolation processing unit 24m. As shown in FIG.
9, the interpolation processing unit 24m identifies parameters
characterizing a system and a signal prediction expression
EVP_si(n) by a predetermined mathematical model (parametric model)
using, as inputs, an ECG waveform as an external input and a
spectrum component from which an estimated response spectrum
component of a transient response is subtracted. The interpolation
processing unit 24m then estimates (calculates) and interpolates a
lost signal by using the identified signal prediction expression
EVPsi(n).
FIGS. 10A, 10B, and 10C are views for explaining the effect of loss
interpolation processing. With the above loss interpolation
processing, for example, interpolating a loss signal estimated as
shown in FIG. 10B for a spectrum having losses as shown in FIG. 10A
can acquire a Doppler spectrum with the loss portions like those
shown in FIG. 10C being interpolated.
Note that such loss interpolation processing is disclosed in, for
example, Jpn. Pat. Appln. KOKAI Publication No. 2001-149370. As a
parametric model, it is possible to use, for example, an AR (Auto
Regressive) model, ARX (Auto Regressive Exogeneous) model, ARMAX
(Auto Regressive Moving Average Exogeneous) model, FIR (Finite
Impulse Response) model, ARARX model, ARARMAX model, or BJ (Box and
Jenkins) model.
The interpolation processing unit 24m includes a memory which
temporarily stores spectrum components corresponding to a plurality
of segments received from the difference processing unit 24l in
chronological order. The interpolation processing unit 24m uses the
spectrum components temporarily stored in the memory to execute the
blend loss interpolation processing of multiplying a spectrum
component corresponding to the front side (temporally past) of each
loss portion and a spectrum component corresponding to the rear
side (temporally future) of each loss portion by a temporally
changing weighting function and adding the products. This blend
loss interpolation processing can acquire a Doppler signal having
smoother time continuity. Using a cosine function as a temporally
changing weighting function, in particular, can efficiently reduce
spike noise generated in two-dimensional spectrum responses.
(Effects)
When performing CWD/B simultaneous mode imaging, this ultrasonic
diagnostic apparatus estimates/calculates a response spectrum of a
transient response excited and generated by noise mixed due to
intermittent transmission/reception upon switching between the
Doppler mode and the B mode, and subtracts the spectrum from a
frequency analysis result. This can reduce the noise component
(offset value) originating from the transient response. As a
consequence, the image quality in CWD/B simultaneous mode imaging
can be improved.
In addition, this ultrasonic diagnostic apparatus identifies a
system by a parametric model using, as inputs, an ECG waveform and
the estimated response spectrum component of the transient
response, and interpolates a lost signal, i.e., a Doppler signal
corresponding to one B-mode frame which is lost by intermittent
transmission/reception due to switching between the Doppler mode
and the B mode. It is therefore possible to interpolate a lost
Doppler signal when performing CWD/B simultaneous mode imaging.
This can reduce the image quality deterioration caused by
losses.
Second Embodiment
The first embodiment described above has exemplified the function
of reducing transient responses originating from the preceding
stage portion (FE) of the wall filter 24b. In practice, however,
weak transient responses are generated by sampling in the wall
filter 24b (for example, in the CWD mode, sampling is performed at
a frequency twice that in the Fourier transform unit 24d) and
sampling for frequency analysis in the window function processing
unit 24c and the Fourier transform unit 24d.
This apparatus may include an arrangement for reducing transient
responses generated in the wall filter 24b, the window function
processing unit 24c, and the Fourier transform unit 24d in addition
to or independently of the arrangement described in the first
embodiment. Note that it is possible to implement the arrangement
for reducing transient responses generated in the wall filter 24b,
the window function processing unit 24c, and the Fourier transform
unit 24d by providing a function substantially similar in effect to
the transient response reduction function described in the first
embodiment for each filter function.
Third Embodiment
According to the first embodiment described above, the difference
processing unit 24l reduces an offset value caused by a transient
response by subtracting the estimated response spectrum component
of the transient response from the spectrum component output from
the Fourier transform unit 24d. In contrast to this, it is possible
to reduce an offset value due to a transient response on the time
axis by changing the size of the offset component (the gain of a
step input) using a step response waveform table of I and Q signals
(2ch) before frequency analysis and subtracting the offset
component from the time axis waveform before frequency
analysis.
Fourth Embodiment
In general, the dynamic range at the preceding stage portion FE
(Front End) of the wall filter 24b may depend on the word length
(the number of bits) of an A/D converter. With the future advent of
a high-speed, high dynamic range A/D converter which can output the
I and Q signals immediately after the mixer and anti-alias filter
or an output from the subsequent stage portion BF (Band-pass
Filter), it is possible to directly calculate a response from the
output and reduce a transient response component by a technique
substantially similar in effect to that in the first
embodiment.
While certain embodiments have been described, these embodiments
have been presented by way of example only, and are not intended to
limit the scope of the inventions. Indeed, the novel embodiments
described herein may be embodied in a variety of other forms;
furthermore, various omissions, substitutions and changes in the
form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
inventions.
* * * * *